I bought borderlanda THC for xbox one few days ago and i wanted to enter a shift code. I created a gearbox acc and confirm e-mail, than i used 2 shift codes.But today codes doesnt work anymore and i only get ,This code is not available for your account" does anyone know what is happening?

I can think of a couple of things, one being that the code isn’t valid for XBox. IIRC you get a slightly different error message for that though. The other possibility is if the code you used wasn’t intended for general use - what was if for, exactly, and where did you find it?